1. Field of the Invention
The present invention relates to a complex cable adapted for being wired under office floors, building floors or the like. The complex cable of the invention is an improved version of the data-transmission cables known in the prior art and used in under-floor wiring.
2. Description of Background Information
Recently, offices have become the main target for applying automation technologies, the so-called xe2x80x9coffice automationxe2x80x9d technologies. In offices, the floors have to be designed so as to provide wiring spaces. The base floors of offices are often covered with panels of a given thickness and tile carpets. These panels and tile carpets are arranged side-by-side and head-to-tail, and form a xe2x80x9cdouble-floor structurexe2x80x9d. The system of this construction is often called a xe2x80x9cfree access floor systemxe2x80x9d.
The panel described above may be a floor panel 1 having a square shape (viewed from the top) with a given thickness, as shown in FIG. 1. This floor panel 1 may be defined by crossing channel portions 4 so as to form, for example, four unitary panel portions 2 having a substantially square shape and integrally bonded to each other via link portions 3. Each of the channel portions 4 has a substantially U-shaped cross-section and a given width, and runs between two unitary panel portions 2. The channel portions 4 can thus serve as wiring paths.
Further, the upper longitudinal side of the channel portions 4, corresponding to the upper side lines of unitary panel portions 2, are provided with steps 5. The channel portions 4 may then be covered with rectangular trench covers 6 or cross-like trench covers 7 by using the steps 5 as rests, so that the top openings of channel portions 4 can be closed.
A floor panel 1 thus formed defines a square (viewed from the top) and the flat floor surface comprises a plurality of unitary panel portions 2 and a plurality of trench covers 6 and 7. A plurality of floor panels 1 are assembled in turn side-by-side and head-to-tail, so that the channel portions 4 extend continuously in crossed directions and form extended channel portions 8. Various kinds of cables may be wired through the channel portions 8. The cables include communications cable units 9 respectively incorporating a plurality of communications cables for data transmission, fiber-optic cables 10 (FIG. 3), electric source cables or the like.
FIG. 2 shows a type of communications cable unit 9 containing a plurality of data transmission cables, e.g. twin-type data transmission cables 17. Such twin-type data transmission cables 17 are manufactured as follows. There is first provided an electrical wire 13 consisting of a conductive element 11 such as copper, and secondly an insulating coating 12 made of polyethylene (PE) or the like surrounding the conductive element 11. A pair of electrical wires 13 prepared in this way is twisted to form a twin-wire strand 14. Four pairs of twin-wire strands 14 are then wrapped with a plastic tape 15 made of polyethylene terephthalate (PET) or PE. The wrapped twin-wire strands 14 are subsequently coated with a sheath 16 made of poly (vinylchloride), i.e., PVC, or the like.
The communications cable unit 9 also comprises an interposition member 18 extending along its axial center line. The interposition member 18 is then surrounded by six groups of such twin-type data transmission cables 17 in substantially parallel relation to one another over the length of the member. Subsequently, the-interposition member 18 and the twin-type data transmission cables 17 are packed with a plastic tape 19 to yield a communications cable unit 9 having an outer diameter of around 15 mm.
The communications cable units 9 described above are often used for short distance communications, e.g., on a one-conductor one-circuit basis. The system is particularly suited for the communications in a same office or building.
By comparison, FIG. 3 shows a known fiber-optic cable 10 which contains inter alia a pair of fiber-optic cords 24. To prepare a fiber-optic cord 24, optical fibers are first covered with a nylon or UV-hardened resin layer, to form a fiber-optic wire 21. The fiber-optic cord 24 comprises a fiber-optic wire 21 thus prepared, a buffer material layer 22 made of aramide fibers, surrounding the fiber-optic wire 21, and a coating made of PVC, surrounding the buffer material layer 22. In addition to the fiber-optic cords 24, the fiber-optic cable 10 contains a tension member 26 extending along its axial center line, as well as a pair of interposition members 25 made of PP yarns or PVC threads. In this construction, the tension member 26 is surrounded by the pair of fiber-optic cords 24 and the pair of interposition members 25 in substantially parallel relation to one another over the length of the member, which are then wrapped with a taping cloth 27. The outer circular surface of taping cloth 27 is further covered with a sheath 28 made of PVC or the like, to give an outer diameter of about 10 mm.
The fiber-optic cables 10 are commonly used for long distance communications, for example, on a one-fiber multiple-transmission basis. The system is particularly suitable for the communications between companies, or between head office and its branch offices. Thereafter, the communications cable units 9 and the fiber-optic cables 10 are wired independently through different process steps. This known wiring process therefore requires many process steps and increases installation costs.
Furthermore, to wire them as separate cables, a larger space is required. However, some office floors may not be able to ensure enough space for such a wiring process.
If such is the case, an optical cable 10 may be forcibly wired in a wire path having insufficient space, and the optical cable 10 thus receives a lateral stress. This lateral stress usually causes a transmission loss.
An object of the present invention is therefore to provide a complex communications cable for under-floor wiring which incorporates data transmission cables and fiber-optic cables. By virtue of this construction, offices may be easily wired, even if the office floors provide little space. This advantage may reduce installation costs.
To this end, there is provided a complex cable for under-floor wiring incorporating at least one fiber-optic cable and a plurality of communications cables for data transmission. The fiber-optic cable includes at least one fiber-optic wire and a first tightening member assembling the at least one fiber-optic wire. The plurality of communications cables for data transmission respectively include at least one twin-wire strand and a second tightening member assembling the at least one twin-wire strand. The at least one fiber-optic cable is surrounded by the plurality of communications cables for data transmission in substantially parallel relation to one another over the length of the fiber-optic cable. The fiber-optic cable and the plurality of communications cables for data transmission are then assembled by a third tightening member.
Preferably, the at least one fiber-optic cable includes at least one interposition member provided in a substantially parallel relation over the length of the at least one fiber-optic wire, and the at least one fiber-optic wire and the at least one interposition member are assembled by the first tightening member.
The above-mentioned first, second and third tightening members may respectively include a plastic tape.
Typically, the at least one fiber-optic wire includes one optical fiber as a core optical element, but it may also include a plurality of optical fibers.
Additionally, the fiber-optic cable may be provided along a central axis of the complex cable, and the plurality of communication cables may be arranged therearound. The complex cable may also be configured such that each communication cable abuts an adjacent communication cable and the fiber-optic cable to provide a closely-packed, compact cable that can be accommodated in narrow spaces.
The complex cable for under-floor wiring may be formed such that each communication cable includes a pair of twisted twin-wire strands, and the fiber-optic cable may include a pair of fiber optic cords and a pair of interposition members altenatingly arranged about a central tension member. Also, the fiber-optic cable may be provided along a central axis of the complex cable, and the plurality of communication cables may be arranged therearound. Moreover, the complex cable for under-floor wiring may be configured such that each communication cable abuts an adjacent communication cable and the fiber-optic cable to provide a closely-packed, compact cable that can be accommodated in narrow spaces.
Additionally, the complex cable for under-floor wiring may be configured with the at least one fiber-optic wire including a taped twin-axial fiber optic wire, a taped quadruple-axial fiber optic wire, or one of a taped quadruple-axial fiber optic wire covered with a buffer material layer and a taped quadruple-axial fiber optic wire covered with a buffer material layer with an outer coating.
In another aspect of the present invention, a method of making a complex cable for under-floor wiring incorporating at least one fiber-optic cable and a plurality of communications cables for data transmission is provided. The method includes providing at least one fiber-optic cable including at least one fiber-optic wire and a first tightening member, wrapping the first tightening member about the at least one fiber-optic wire, providing a plurality of communications cables for data transmission respectively including at least one twin-wire strand and a second tightening member, and wrapping the second tightening member about the at least one twin-wire strand.
The method further includes simultaneously feeding the at least one fiber-optic cable and the plurality of communication cables such that the at least one fiber-optic cable is surrounded by the plurality of communications cables for data transmission in a substantially parallel relation to one another over a length of the at least one fiber-optic cable to form an assembled strand, and wrapping a third tightening member about the assembled strand to form a closely-packed, compact cable that can be accommodated in narrow spaces.
Additionally, the method of making a complex cable may also include providing the fiber-optic cable along a central axis of the complex cable with the plurality of communication cables arranged therearound such that each communication cable abuts an adjacent communication cable and the fiber-optic cable to provide the closely-packed, compact cable that can be accommodated in narrow spaces.